The present invention relates generally to battery cells and more particularly to a battery cell design including a battery cell component, a battery cell having the component, a battery pack assembly, and a method of cooling battery cells in the battery pack assembly.
Battery cells, depending on the particular technology employed, have optimal or improved performance in certain temperature ranges. Performance and/or degradation rates worsen when operated outside the temperature ranges. Accordingly, various thermal control systems are employed to aid in getting the battery cell to operate within the temperature range.
One thermal management method used with sodium-based battery cells is employing a system having an electric heater plate located at the top of the battery cells and a series of interstitial air cooling structures or panels. The air-cooling structures or panels are located between the rows of battery cells, which are typically arranged in a cell array (i.e., battery cell assembly). When battery cooling is needed, air is pushed through the duct of the cooling panel, thereby directing air first to the outside casing of the battery cells. Meanwhile, heat transfer is from the core of the cell to the air via the anode compartment; then the cell case steel wall; then the electrical insulation; then the wall of the cooling panel; and, then finally to the air. A disadvantage of this system is the indirect cooling of the core of the cell and the long path for the heat flow from the source to the sink. Additionally, the anode compartment is only partially filled with sodium, which is a good conductor. In fact, under normal operating conditions, the Na level in the anode compartment typically never exceeds about 40% of the available volume at any stage of the charge/discharge cycle. This method is limited in terms of how fast and how effective the cathode will be cooled to keep its temperature in the desired operating ranges under cycling conditions. This method is therefore cumbersome, heavy, expensive, and inefficient.
Accordingly, there is an ongoing need for improving upon the effectiveness of the various thermal management methodologies for battery cells.